This invention relates to wood trim, of the kind used to trim the edges of door frames and window frames, wainscotting, and also baseboards and skirting boards, in houses and other buildings.
In the conventional manner of applying such trim, for instance around a door frame in a house, the carpenter cuts the lengths of trim, mitres the corners, and then nails the lengths of trim in place; then he drives the nail heads below the surface of the trim; he applies filler or stopper into the indentations; and leaves the filler to set. He returns later, and smooths down the filler. After that he applies stain, varnish, etc as required.
A good deal of care and attention is required of the carpenter when fitting conventional door trim. The door trim is very visible and noticeable, and if the job is done casually or carelessly the results can be most displeasing to the householder.
One problem with conventional trim is that finishing coatings cannot be applied to the trim until after the trim has been nailed up, and the nail-holes have been filled and smoothed. Especially when the trim is being applied to a new house the atmosphere is likely to be dusty, and dust can spoil the quality of the finish. Only a conscientious carpenter, working with a great care and attention, can be left with the job of applying and finishing the trim, especially if the trim is of the kind in which the decorative grain of the wood is to be displayed.
If the trim is to be painted, rather than left with the natural grain visible, the amount of attention needed to fill the nail holes, etc can be reduced. Consequently, it has been unusual for builders to provide wood trim in which the natural grain is left showing: the builder has far rather preferred to cover the trim over with paint, since the quality of craftsmanship needed to do that is rather lower.
The invention is aimed at providing a means for attaching wood-trim around a door frame, etc, which is far simpler for the carpenter than the above, and in which nothing (such as nail heads) mars the presentation-surface of the trim. It is an aim of the invention that the trim may be pre-finished, in-factory if desired, and applied to the wall in its finished form.
The invention provides a wood trim assembly, which is suitable for attaching solid wood door and window trim, wainscotting, baseboard trim, or the like to a wall. The assembly includes lengths of solid wood trim, and lengths of spline. Each length of wood trim is of constant cross-section along its length, as is each length of spline. The pieces of the trim are assemblable to the splines.
Each length of the solid wood trim includes a back face which is adapted to lie flat against the wall, and a decorative front surface. The shape of the cross-section of the solid wood trim includes a groove formed into the cross-section of the trim from the back face.
The spline is adapted to fit inside the groove in the trim, in that the cross-section of the groove is complementary in shape and size to the cross-sectional shape and size of the spline.
The spline is adapted to be fixed firmly to the wall, prior to the trim being assembled to the spline. The fit of the spline to the groove in the trim is such that, upon assembly of the trim to the spline, the spline being fixed firmly to the wall, the trim is assemblable over the spline by means of a manual (light) pounding action, whereby the trim, after assembly, remains firmly held in place by means of its frictional grip on the spline, and whereby the use of nails or glue to hold the trim is avoided.
The fact that the trim is held by a mechanical friction grip, and not by nails, nor glue, means that the trim is removable. This is an important feature of the invention, in that the trim can be taken off for such purposes as painting or papering the walls around a door frame, or for replacing a damaged piece of trim. Notwithstanding the fact that the trim is removable, the decorative surface of the trim is not subject to any compromise arising from the manner of attachment of the trim. The surface remains clear, whether the trim is removed and replaced often, or remains in place more or less permanently.
The fit of the groove to the spline, after assembly, across the width of the groove, preferably is between zero clearance and xc2xc mm clearance.
Preferably, one of either the groove or the spline is tapered, to the extent that the clearance between the groove and the spline, upon presentation of the groove to the spline just prior to assembly is about xc2xd mm, on the basis that the groove is less than about 15 mm in width.
It is not intended that the wood trim should flex and snap over a bead of any kind, but rather that the tightness of the fit of the trim onto the spline arises because of the rigidity of the trim. For this reason, it is preferred that the cross-sectional shape of the trim, with the groove therein, is characterised as chunky and rigid.
The spline may be of wood or of plastic. If the latter, the cross-sectional shape of the spline may include resilient fingers which, upon assembly of the trim to the spline, engage, and press resiliently against, the sides of the groove.
The pieces of trim and the splines may be included as components of a kit, which also includes a jig for assisting in the accurate placing of the splines in the desired location on the wall.
The jig includes a spline holder, in which is formed a jig-groove, the jig-groove being complementary in cross-sectional size and shape to the spline. The jig is provided with through-holes, which are so positioned and arranged that screws can pass therethrough and through a spline positioned in the jig-groove, the through-holes in the jig being large enough that the heads of the screws can pass through the through-holes in the jig.
When the trim is being applied around the corners of a door frame, the jig includes two such spline holders, and the jig includes a brace for holding the two holders precisely set at right angles to each other. Preferably, the jig includes an abutment piece, which is so arranged as to provide an abutment for locating and positioning the jig flat against the jamb of a door frame.
Preferably, the abutment piece is no more than 2 mm thick, and is so located and arranged as to fit, in use of the jig, between the lintel of a door frame and the top of a door in the door frame.
When the jig is adapted for mounting wainscotting or baseboard trim, the groove is set a first distance from a first abutment surface on the jig, which is adapted to rest on the floor during use of the jig, and the groove is set a second distance from a second surface abutment which is adapted to rest on a carpet on the floor during use of the jig, the second distance being about 12 mm shorter than the first distance. This allows the jig to be used either on the bare floor, or with the room carpet in place.
Because the trim requires no nails etc to hold it in place, the trim can be pre-finished, ie the trim requires no painting etc after being assembled; therefore the ability to fit the trim accurately with the carpet in place, is highly convenient. (If the trim had to be finished, ie painted or varnished, after installation the prudent householder might wish to take up the carpet in any event.)
Optionally, the assembly includes a pair of the said grooves and a complementary pair of the said splines, the splines being linked by a web means, which is effective to hold the splines in a precise, spaced-apart, parallel side-by-side relationship.
Optionally also, the shape of the cross-section of the solid wood trim includes a cut-out which is suitable for receiving electrical wiring passing along the length of the trim, and the web is formed with an alignment means for aligning the wiring with respect to the web prior to assembly of the trim to the splines. This option is particularly advantageous when the two parallel splines are provided, because then it is simple to provide an alignment ledge or channel against which the wiring can be fixed, prior to assembly of the trim.
The fact that the trim is removable means that the addition of wiring later into a room can be accomplished very conveniently.
As mentioned, preferably the groove and the spline are plain-sided, in that the sides of the grooves and splines include no protrusions or beads or re-entrant aspects, and in that the fit of the trim to the spline is such that the wood of the trim is not required to flex resiliently, upon engagement. Wood might split if required to do that.
The invention also consists in a procedure for attaching solid wood door and window trim, wainscotting, baseboard trim, or the like, to a wall. The procedure includes the step of providing a length of solid wood trim, and lengths of spline; of providing a groove in the trim which is complementary in cross-sectional size and shape to the cross-section of the spline; of fixing the spline solidly to the wall by means of fasteners; of applying the trim over the spline, whereby the groove in the trim engages the spline; and of so dimensioning the groove and the spline that, upon engagement, the sides of the groove are in contact with the sides of the spline, thereby creating a frictional resistance to the dislodgement of the trim from the spline.
Of prior patent publications, DE-3,205,671 shows a trim attachment system where a spline engages a groove in a direction parallel to the wall. DE-3,842,687 shows a trim attachment system where a baseboard is arranged to stand-off from the wall. GB-2,239,281 shows a trim attachment system where a spline is a tight interference fit in a groove.